Psyching Us Out: The Promises of ‘Priming’

By GARY GUTTING

October 31, 2013

Reports of psychological experiments are journalistic favorites. This is especially true of experiments revealing the often surprising effects of “priming” on human behavior. Priming occurs when a seemingly trivial alteration in an experimental situation produces major changes in the behavior of the subjects.

The classic priming experiment was one in which college students had been asked to form various sentences from a given set of words. Those in one group were given words that included several associated with older people (like bingo, gray and Florida). Those in a second group were given words with no such associations. After the linguistic exercise, each participant was instructed to leave the building by walking down a hallway. Without letting the participants know what was going on, the experimenters timed their walks down the hall. They found that those in the group given words associated with old people walked significantly slower than those in the other group. The first group had been primed to walk more slowly.

Similar experiments have revealed a cascade of priming effects, operating on a range of human behaviors. People primed with thoughts of larger numbers say they are willing to pay more for merchandise and give higher estimates of people’s ages or the size of cities. Those primed by engaging in abstract thought are more willing to agree with the idea of killing one person to harvest organs to save the lives of many others, while those who have been thinking of money are less willing to help strangers who have dropped pencils. (There is now some controversy raised by experimenters who have been unable to replicate some priming effects. This needs sorting out, but the sheer number of reported effects over many years makes it unlikely that the phenomenon will turn out not to be real.)

Priming experiments are fascinating to read about, provide great conversation starters, and are good reminders of how vulnerable we are to irrational forces. But much more is claimed for them. It is often said that they overturn a long entrenched view of human beings as models of rationality. A review in “The Economist” of Daniel Kahneman’s “Thinking Fast and Slow”(a book that summarizes a great deal of work on priming and related phenomena) says: “As Copernicus removed the Earth from the centre of the universe and Darwin knocked humans off their biological perch, Mr Kahneman has shown that we are not the paragons of reason we assume ourselves to be.” Such judgments ignore the enormous emphasis religious, philosophical, and literary writers have placed on our irrationality, and mistake homo economicus, the idealized rational actor of economic theory, for the prevailing human self-conception.

Apart from grandiose claims about their philosophical significance, priming experiments are often thought to provide powerful new tools for influencing human behavior. The financial magazine Forbes and Morningstar, the investment research firm, have cited the immense practical value of what they call “behavioral economics” (a common but odd name for applications of psychological research on priming). But a closer analysis does not support such claims.

The reason is that priming experiments seldom tell us how important priming is in realistic situations. We know that it has striking effects under highly simplified and controlled laboratory conditions, where the subjects are exposed only to the stimuli that the experimenters provide. But it is very difficult to know how significant priming stimuli (thinking about money, large numbers, abstract questions) would be in a real-life, uncontrolled environment, where all sorts of stimuli might be conflicting with one another. Also, there is seldom any reason to think that even a strong priming effect will last very long. As Jonathan Ellis has noted, even Kahneman ignores these points when, after summarizing the walking-like-the-elderly experiment, he says: “Although you surely were not aware of it, reading this paragraph [which contained many words relating to the elderly] primed you as well. If you had needed to stand up to get a glass of water, you would have been slightly slower than usual to rise from your chair . . . ”

John Bargh, one of the main researchers on priming, acknowledged in a 2006 article the failure to extend priming to real-life situations. (This is what experimenters call the problem of “ecological validity.”) Priming studies, he said, had come to their “childhood’s end.” Now “we must seek to extend the findings of nonconscious perceptual, appraisal, motivational, and behavioral effects from our laboratories, where they have mainly been studied in isolation from each other, into the complex and noisy real world in which they all combine, somehow, to drive our actions.” However, in their detailed 2012 survey of recent work on priming, Bargh and colleagues cite only laboratory experiments and a few “field experiments,” where circumstances in the real world are, for a brief period, carefully controlled.

There is no automatic transfer of a laboratory result to the real-world events we want to control. In the natural sciences we can typically control and probe inert bodies any way we like to yield precise quantitative measures of effects. But the complexity of humans, the interdependence of key variables, and ethical limitations on constraining human subjects make such control far less likely in the human sciences.

These limits are well illustrated by Richard Thaler and Cass Sunstein’s best-selling book, Nudge. The authors begin with excellent discussions of priming and similar experimental results and then put forward numerous public policy proposals, most of them quite sensible, allegedly inspired by these results. But hardly any of their proposals depend on the results of behavioral economics. Their ideas are mostly a matter of common sense or of strategies long practiced in the business world: in giving people options (regarding decisions like retirement plans or organ donations), make the choice you prefer the default option; provide more or less information on a credit card bill depending on whether you want people to pay just the minimum each month; arrange food in a cafeteria or supermarket so the items you want chosen are most accessible. As Benjamin Friedman pointed out in his review of the book, “we don’t need behavioral economics . . . to think such proposals might be helpful.”

Priming experiments remain important sources of information about the details of how our minds work. It’s possible that they might someday yield valuable techniques for modifying real-world behavior. (Here is one promising if very preliminary example.) But for now claims that they have deep philosophical significance or major practical consequences have scant support.

Gary Gutting is a professor of philosophy at the University of Notre Dame, and an editor of Notre Dame Philosophical Reviews. He is the author of, most recently, “Thinking the Impossible: French Philosophy since 1960,” and writes regularly for The Stone. He was recently interviewed in 3am magazine.